A general example of a fabric filter system is disclosed in U.S. Pat. No. 4,336,035. Such a fabric filter system typically comprises a plurality of filter bags, which separate particulate matter from a gas flow. A typical application of such a fabric filter system is to clean flue gases from a coal combustion process.
In some cases, it is desired to substantially stop gas from flowing through at least a portion of the fabric filter system. One such case, for example, is to allow service staff to enter the interior of one filter module of the fabric filter system, while filtering continues in other, parallel filter modules within the same fabric filter system.
Termination of gas flow through at least a portion of a fabric filter system may be provided by means of a flow control device. The flow control device, such as a flap damper, may be devised as a hinged door pivotably moveable between two positions. One position whereby the hinged door does not cover the filter module opening to the outlet duct, i.e., open position, and one position whereby the hinged door does cover the filter module opening to the outlet duct, i.e., closed position.
One problem associated with such a filter modules is that the hinged door may be difficult to operate. In particular, this is a problem if the filter module opening is large thereby requiring a large hinged door to cover the same. In such a case, considerable force is needed to move the hinged door from one position to the other.